Because this kind of reply gets posted every single time sleep deprivation is brought up.
Needing this little sleep is usually a lie or a self-delusion. Perpetuating it has negative consequences for the rest of us. Do some of these unicorns exist? Sure. But they are nowhere near as common as this type of comment suggests. Most of the people in question would be better off with more sleep.
Can they survive on 5 hours? Sure. Most of us can also survive on nothing but pizza. Doing this doesn't make you different, just unhealthy.
Do you have data showing that it's "usually a lie or self-delusion"? Because there's a genetic explanation[1] for why folks need less sleep. The only way I can sleep 9 hours in a night is if I work up a sleep debt.
That one mutation is rare, but it's an advantageous one in a society of workaholics, so there's probably a sampling bias: we're more likely to encounter folks with that mutation when selecting for high performers. It's also a single mutation -- there may be others that provide a similar, if more moderate, effect.
How can you be sure it's not a lie? What I meant by "lie" is this: let's say you ask someone how much they sleep. Currently society tells us that working as much as possible is a virtue. So they tell you they sleep 4 hours every night. You have no way of verifying this information. For all you know they could be sleeping 8 or 9 hours. But it is very easy and tempting for them to lie for a small boost in social standing.
Because these people are exceedingly rare. I get 5 hours of sleep a night because I have some pretty bad lifestyle choices. The few weeks where I have a normal sleep schedule I am absolutely a different person.
I mean I can function on 5-hours, I'm able to hold a job and live a life; but my well being could be so much better if I got a normal nights sleep everyday.
